We use a really simple custom wiki. I don't know who/what team in the company made it, but the left side of the page is just boxes (headings) with links (subheadings). The main bulk of the page is an iframe (again, I didn't make it and not what I'd use) that loads the link clicked on (theory is to keep the url static and prevent linking to specific sections, again I'm not on this team). I can't share pictures for legal reasons, but my email is in the bio if you want to talk further.

Works extremely well, though. Non-tech-savy people can even fly around it, and people with a special cookie get editing rights. No need to over engineer it really, if it's just documentation you could even make a private subreddit and use the wiki feature there, giving editing rights to some users and preserving a commit-style edit history.

Even the Apple OS X (or what used to be called OS X) Server app has a wiki built in.